Burn Scar Thickness Predicts Dyschromia Presence and Delayed Resolution in a Black Patient Cohort

Abstract Introduction Post-burn dyschromia is highly prevalent in skin of color and leads to psychosocial complications for these patients. There are no treatments for this pathophysiology due to a limited understanding of its mechanism. Therefore here, potential drivers of hyperpigmentation were studied. It was hypothesized that dermal fibroblast-driven scar thickness is the dominant driver of dyschromia occurrence and persistence, outweighing burn size and acute critical illness. Methods This was a retrospective analysis of Black patients (13.3%) in The Burn Model Systems Database (n = 2827) at discharge, 1-, 6-, 12-, and 18-months post-discharge. Variables were recorded as: scar thickness (yes/no), dyschromia (yes/no), %TBSA burned, and ventilator days (a proxy for acute critical illness). Cross-sectional analysis was performed at the discharge timepoint. Associations were tested by Pearson correlations, Wilcoxon tests, and Fisher’s exact tests. Multivariable logistic regression (n = 142) modeled dyschromia with predictors of scar thickness %TBSA, ventilator days (≤4/4 days). Effect modification by TBSA and ventilation was tested. Time-to-resolution of dyschromia was analyzed using Kaplan–Meier, Cox proportional hazards with age and sex, and the Weibull accelerated failure time (AFT) model. Results At discharge, dyschromia and scar thickness were present in 163/177 (92%) and 95/161 (59%) subjects, respectively. Thickness correlated with dyschromia (r = 0.31). Thickness and dyschromia was strongly associated; Fisher OR = 21.0, 95% CI 2.95-914.9, p.001. In logistic models, thickness remained the only independent predictor (OR = 22.0, 95% CI 3.9-418.3, p=.004), while %TBSA and ventilator days were not significant and no significant interactions between other variables were detected. Dyschromia resolved faster in thin scars (log-rank, p=.0068). In Cox models, thick scars had markedly slower resolution (HR = 0.05, p=.004); and the Weibull AFT estimated an acceleration factor of 24.3 (95% CI 1.75-337, p=.017), consistent in the direction and magnitude with the Cox model. Conclusions Scar thickness, not burn size nor critical illness, dominates both the presence and persistence of dyschromia in this Black cohort, supporting a mechanistic model in which fibroblast-mediated dermal fibrosis affects epidermal pigment dysregulation. Applicability of Research to Practice Scar treatments that modulate dermal fibrosis should be explored and include dyschromia resolution as a key endpoint, particularly for patients with skin of color. Funding for the study This work was funded in part by award number KL2TR001432 from the National Center for Advancing Translational Science (NCATS/NIH).